It is common in the production field to use a reciprocating pumping system to pump the production fluid from the well up to the surface.
On occasion it is necessary or desirable to inject or circulate a fluid down into the hole and around the foundation of the production zone, such as various chemicals, steam, etc. In the prior art, for such to take place, the production operator had to pull the entire production string out of the hole and bring in a separate work-over rig at very great cost (e.g. $5,000 to $20,000/day) requiring relatively highly skilled engineers and causing a substantial amount of down time (e.g. two and a half days).
Furthermore, the injection of steam and other formation treating chemicals results in the corrosion and ultimate destruction of the string. The presence of silica sand and hydrogen sulfide (H.sub.2 S), common in formations, add further corrosion problems. Currently, a production string may last only fifteen (15) days when these problems are encountered. This significantly adds to the cost and efficiency of the oil production process.
Using the tool and methodology of the present invention, all of this is avoided, with substantial savings in energy production costs. With the invention's tool at the end of the production string, the operator using, for example, two rough-necks or roustabouts, basically merely changes the state of the tool from its production flow or pumping disposition to its fluid injection state by merely twisting the internal part of the tool down in the hole by, for example, about ninety (90.degree.) degrees, and allowing or causing an internal part to longitudinally move with respect to the outer part(s), and injecting the fluid down through the production string. Once the fluid is injected, the rough-necks or roustabouts merely twist the tool back to its production state and re-initiate production, all with relatively little down time and relatively little expense.
Further, a production string is provided in which the plunger and barrel elements have an anti-corrosive inner "lining" and an anti-abrasive outer "lining". Thus the corrosion problems encountered in the presence of hydrogen sulfide and silica sand, or when steam and/or chemicals are injected, are obviated. The lifespan of the production string is greatly extended beyond the current fifteen days to at least two years.
For general informational purposes, it is noted that the inventor hereof became aware of a back-wash tool, designed by Spears Specialty Oil Tools, Inc. of Tomball, Tex., in which tool there were two, in-line ball valves, in which the bottom one was designed to be knocked off of its seat, when so desired, by the use of a downwardly and sidewardly moving, spoon-like structure, which didn't work reliably and only provided a relatively small opening rather than the full bottom opening of the present invention. A patent issued to Spears (U.S. Pat No. 5,382,142) on Jan. 17, 1995.
Thus, in contrast, the present invention overcomes the prior art problems by providing a down-hole circulation system which is safe, reliable, easy and inexpensive to use, saving many thousands of dollars on a regular basis over the prior art approaches, while also providing significant energy savings and enhanced pollution prevention.